The 22-year-old was forced off at half-time in the Sky Blues’ 2-1 defeat to Sheffield United on Wednesday.
Coventry manager Chris Coleman has confirmed that Fox is a major doubt for the visit of Chelsea, due to a knee problem.
“We will have to wait and see but at the minute it doesn’t look very good,” he said.
“I am not saying long-term but, he could struggle for the weekend. But I am not too bothered about him missing Saturday.
“I would much rather have him fit and available for the league games against Bristol City and Preston.”
